Annelida - "Ringed Worm"
Leech
Leeches are hermaphrodites, possessing both male and female organs. Reproduction occurs from the intertwining bodies of two worms and the sperm is collected by the female. Male leeches do not have a penis, but instead they have sharp packages of sperm that disperse when engaging in sexual reproduction. Some leeches are parasites and rely on blood from their host to live and thrive. Their host are normally animals in the wild such as birds and sometimes even humans. However, a lot of leeches eat other small organisms such as earthworms to survive. Leeches are very adaptive to their environment, and can even survive in very low oxygen areas.
Earthworm
Earthworms are just hermaphrodites like other worms or leeches. They reproduce sexually in order to give birth to their offspring. After sexual reproduction, the fertilized eggs form in slime tubes and form into tiny cocoons. These eggs take up to 3-4 months to mature fully. The mother lays the eggs in tiny cocoons that are usually a third of an inch long. Each cocoon contains 10-15 baby worms. When they are born they are very small and grow into the familiar sized worms we see today. Since earthworms have both female and male reproductive organs, they don't need to look very far in order to reproduce. They can literally reproduce with any other earthworm.
Bristle Worm
Bristle is another word for "marine." These worms live and reproduce underwater. This worm is unique in the amount of ways it can give birth to it's offspring. It can either dismantle a small piece of itself from it's body and let that grow into an individual bristle worm. This is it's form of asexual reproduction. Like other worms, the bristle worm is a hermaphrodite. It has both female and male reproductive organs. It can also undergo sexual reproduction with a partner, which is more beneficial due to the amount of variation you would get as opposed to asexual reproduction. The bristle worm can either lay eggs or it can make small cocoons similar to the earthworm's.